Diagnosis of disorders in amino acid methabolism by chemical ionization mass spectrometry.

A semi-quantitative method has been developed for rapid determination of amino acids and other nitrogenous compounds in human urine. The method uses direct chemical ionization mass spectrometry with isobutane as reagent. The nitrogenous compounds are separated from the urine samples by ion exchange. Disorders in amino acid metabolism have been determined by this method in patients suffering from phenylketonuria, cystinuria and maple-syrup urihe disease.